The present invention relates to a method of making semiconductor devices using a silicon carbide hard mask.
Semiconductor devices include metal layers that are insulated from each other by dielectric layers. As device features shrink, reducing the distance between the metal layers and between metal lines on each layer, capacitance increases. To address this problem, insulating materials that have a relatively low dielectric constant are being used in place of silicon dioxide to form the dielectric layer that separates the metal lines.
Certain materials that may be used to form low k dielectric layers (e.g., those comprising organic polymers) must be protected, when certain processes are used to remove photoresist, or other substances, from their surfaces. In a commonly used technique to protect such materials, a hard mask is formed on their surface prior to depositing photoresist, or other substances, on top of them. Such a hard mask may be formed from silicon carbide. Although silicon carbide may adequately protect an underlying dielectric layer during subsequent process steps, this class of materials is hydrophobic. Silicon carbide""s hydrophobic nature renders it difficult to clean its surface, and to bond it to other layers. In addition, materials that are coated onto silicon carbide may lack desirable thickness uniformity.
Current methods for addressing silicon carbide""s undesirable attributes employ adhesion promoters and certain chemical solutions, which modify surface chemistry to facilitate surface cleaning. Such methods require the use of relatively expensive chemicals. Accordingly, there is a need for an improved process for making a semiconductor device using a silicon carbide hard mask. There is a need for such a process that converts a hydrophobic silicon carbide surface to a hydrophilic one in a relatively inexpensive and unobtrusive manner, enabling improved adhesion characteristics and facilitating surface cleaning. The method of the present invention provides such a process.